GM-GMC: 1987 gmc 3500 brake problem, tire air pressure, gmc 3500

Question
I have a 1987 gmc 3500 with a 350tbi 2wd and dual tires in the rear.  My problem is that when i step on the brake the truck wants to pull to the right and when i let off the brake the caliper sticks and it wants to pull to the left.  So i replaced the calipers and brakes and rotors and bled the lines but it's still doing the same thing.  Any ideas?
thank you,
Sean

Answer
I have the same type of problem with my 83 G-20, except mine pulls to the left.

Start with the basics:  Check the tire air pressure.

Other than that, suspension/steering parts may be worn.  Brake hoses may be going bad internally.  The brake proportioning valve may be bad.  Even rear suspension parts that are worn can cause this type of problem.

I will be changing my front suspension bushings in a few weeks.  I will know then if they are cuaisng the problem with my vehicle.